An electronic device, such as a tablet or an electronic book reader, may include a number of layers. The layers may include, for example, a back plate, a display, a touch sensor, cover glass, or any other layer. The layers may be coupled together by an adhesive sandwiched between the layers. The adhesive may be an optically clear adhesive. For example, a cover layer may be coupled to an underlying display layer by an optically clear adhesive such that viewing of the display by a user of the electronic device is not disturbed by the adhesive.
During manufacture of the electronic device, care may be taken to ensure that application of the adhesive between two layers is uniform. Deviations from a uniform application of the adhesive (such as bubbles in the adhesive, delamination of the adhesive, or other defects) may be visible to a user of the electronic device and disturb the viewing of the display by the user.